Implementing VRRP

The Virtual Router Redundancy Protocol (VRRP) feature allows for transparent failover at the first-hop IP
router, enabling a group of routers to form a single virtual router.
Feature History for Implementing VRRP
Release

Modification

Release 2.0

This feature was introduced.

Release 3.4.0

This feature was updated to support the minimum and reload

delay options.

Release 3.5.0

VRRP supports Ethernet link bundles.

Release 3.7.0

The clear vrrp statistics command was introduced

Release 3.9.0

BFD for VRRP feature was added.

MIB support for VRRP feature was added.
Hot Restartability for VRRP feature was added.

Release 4.1.0

VRRP over IPv6 feature was added.

Prerequisites for Implementing VRRP on Cisco IOS XR Software, page 2

Information About Implementing VRRP , page 2
How to Implement VRRP on Cisco IOS XR Software , page 5
Configuration Examples for VRRP Implementation on Cisco IOS XR Software , page 11
MIB support for VRRP, page 21
Hot Restartability for VRRP, page 22
Configuration Examples for VRRP Implementation on Cisco IOS XR Software , page 23

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Prerequisites for Implementing VRRP on Cisco IOS XR Software

Additional References, page 24

Prerequisites for Implementing VRRP on Cisco IOS XR Software

You must be in a user group associated with a task group that includes the proper task IDs. The command
reference guides include the task IDs required for each command. If you suspect user group assignment is
preventing you from using a command, contact your AAA administrator for assistance.

Information About Implementing VRRP

To implement VRRP on Cisco IOS XR software , you need to understand the following concepts:

VRRP Overview
A LAN client can use a dynamic process or static configuration to determine which router should be the first
hop to a particular remote destination. The client examples of dynamic router discovery are as follows:
Proxy ARPThe client uses Address Resolution Protocol (ARP) to get the destination it wants to reach,
and a router responds to the ARP request with its own MAC address.
Routing protocolThe client listens to dynamic routing protocol updates (for example, from Routing
Information Protocol [RIP]) and forms its own routing table.
IRDP (ICMP Router Discovery Protocol) clientThe client runs an Internet Control Message Protocol
(ICMP) router discovery client.
The drawback to dynamic discovery protocols is that they incur some configuration and processing overhead
on the LAN client. Also, in the event of a router failure, the process of switching to another router can be
slow.
An alternative to dynamic discovery protocols is to statically configure a default router on the client. This
approach simplifies client configuration and processing, but creates a single point of failure. If the default
gateway fails, the LAN client is limited to communicating only on the local IP network segment and is cut
off from the rest of the network.
The Virtual Router Redundancy Protocol (VRRP) feature can solve the static configuration problem. VRRP
is an IP routing redundancy protocol designed to allow for transparent failover at the first-hop IP router. VRRP
enables a group of routers to form a single virtual router . The LAN clients can then be configured with the
virtual router as their default gateway. The virtual router, representing a group of routers, is also known as a
VRRP group.
For example, Figure 1: Basic VRRP Topology, on page 3 shows a LAN topology in which VRRP is
configured. In this example, Routers A, B, and C are VRRP routers (routers running VRRP) that compose a

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Multiple Virtual Router Support

virtual router. The IP address of the virtual router is the same as that configured for the interface of Router A
(10.0.0.1).
Figure 1: Basic VRRP Topology

Because the virtual router uses the IP address of the physical interface of Router A, Router A assumes the
role of the master virtual router and is also known as the IP address owner. As the master virtual router,
Router A controls the IP address of the virtual router and is responsible for forwarding packets sent to this IP
address. Clients 1 through 3 are configured with the default gateway IP address of 10.0.0.1.
Routers B and C function as backup virtual routers. If the master virtual router fails, the router configured
with the higher priority becomes the master virtual router and provides uninterrupted service for the LAN
hosts. When Router A recovers, it becomes the master virtual router again.

Note

We recommend that you disable Spanning Tree Protocol (STP) on switch ports to which the virtual routers
are connected. Enable RSTP or rapid-PVST on the switch interfaces if the switch supports these protocols.

Multiple Virtual Router Support

You can configure up to 255 virtual routers on a router physical interface. The actual number of virtual routers
that a router interface can support depends on the following factors:
Router processing capability
Router memory capability
Router interface support of multiple MAC addresses

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VRRP Router Priority

In a topology where multiple virtual routers are configured on a router interface, the interface can act as a
master for one or more virtual routers and as a backup for one or more virtual routers.

VRRP Router Priority

An important aspect of the VRRP redundancy scheme is VRRP router priority. Priority determines the role
that each VRRP router plays and what happens if the master virtual router fails.
If a VRRP router owns the IP address of the virtual router and the IP address of the physical interface, this
router functions as a master virtual router.
Priority also determines if a VRRP router functions as a backup virtual router and determines the order of
ascendancy to becoming a master virtual router if the master virtual router fails. You can configure the priority
of each backup virtual router with a value of 1 through 254, using the vrrp priority command.
For example, if Router A, the master virtual router in a LAN topology, fails, an election process takes place
to determine if backup virtual Routers B or C should take over. If Routers B and C are configured with the
priorities of 101 and 100, respectively, Router B is elected to become master virtual router because it has the
higher priority. If Routers B and C are both configured with the priority of 100, the backup virtual router with
the higher IP address is elected to become the master virtual router.
By default, a preemptive scheme is enabled whereby a higher-priority backup virtual router that becomes
available takes over for the backup virtual router that was elected to become master virtual router. You can
disable this preemptive scheme using the no vrrp preempt command. If preemption is disabled, the backup
virtual router that is elected to become master virtual router remains the master until the original master virtual
router recovers and becomes master again.

VRRP Advertisements
The master virtual router sends VRRP advertisements to other VRRP routers in the same group. The
advertisements communicate the priority and state of the master virtual router. The VRRP advertisements are
encapsulated in IP packets and sent to the IP Version 4 multicast address assigned to the VRRP group. The
advertisements are sent every second by default; the interval is configurable.

Benefits of VRRP
The benefits of VRRP are as follows:
Redundancy VRRP enables you to configure multiple routers as the default gateway router, which
reduces the possibility of a single point of failure in a network.
Load SharingYou can configure VRRP in such a way that traffic to and from LAN clients can be
shared by multiple routers, thereby sharing the traffic load more equitably among available routers.
Multiple Virtual RoutersVRRP supports up to 255 virtual routers (VRRP groups) on a router physical
interface, subject to the platform supporting multiple MAC addresses. Multiple virtual router support
enables you to implement redundancy and load sharing in your LAN topology.
Multiple IP AddressesThe virtual router can manage multiple IP addresses, including secondary IP
addresses. Therefore, if you have multiple subnets configured on an Ethernet interface, you can configure
VRRP on each subnet.

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How to Implement VRRP on Cisco IOS XR Software

PreemptionThe redundancy scheme of VRRP enables you to preempt a backup virtual router that has
taken over for a failing master virtual router with a higher-priority backup virtual router that has become
available.
Text AuthenticationYou can ensure that VRRP messages received from VRRP routers that comprise
a virtual router are authenticated by configuring a simple text password.
Advertisement ProtocolVRRP uses a dedicated Internet Assigned Numbers Authority (IANA) standard
multicast address (224.0.0.18) for VRRP advertisements. This addressing scheme minimizes the number
of routers that must service the multicasts and allows test equipment to accurately identify VRRP packets
on a segment. The IANA assigns VRRP the IP protocol number 112.

How to Implement VRRP on Cisco IOS XR Software

This section contains instructions for the following tasks:

Note

The VRRP virtual router id (vrid) has to be different for different sub-interfaces, for a given physical
interface.

Customizing VRRP
Customizing the behavior of VRRP is optional. Be aware that as soon as you enable a VRRP group, that group
is operating. It is possible that if you first enable a VRRP group before customizing VRRP, the router could
take over control of the group and become the master virtual router before you have finished customizing the
feature. Therefore, if you plan to customize VRRP, it is a good idea to do so before enabling VRRP.
The sections that follow describe how to customize your VRRP configuration.

SUMMARY STEPS
1. configure
2. router vrrp
3. interface type interface-path-id
4. address-family {ipv4 | ipv6}
5. vrrp vrid version { 2 | 3 }
6. text-authentication
7. accept-mode{disable}
8. priority priority
9. preempt [delay seconds] [disable]
10. timer [msec] interval [force]
11. track interface type instance interface-path-id [priority-decrement]
12. delay [minimum seconds] [ reload seconds]
13. Use the commit or end command.

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DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

router vrrp

Enables VRRP configuration mode.

Example:
RP/0/RP0/CPU0:router(config)# router vrrp

Step 3

interface type interface-path-id

Enables VRRP interface configuration mode on a specific

interface.

Example:
RP/0/RP0/CPU0:router(config-vrrp)# interface
TenGigE 0/2/0/1

Step 4

address-family {ipv4 | ipv6}

Enters the IPv4 or IPv6 address family submode.

Example:
RP/0/RP0/CPU0:routerconfig-vrrp-if)#
address-family ipv6

Step 5

vrrp vrid version { 2 | 3 }

Enters the virtual router configuration submode.

Note

Example:

The version keyword is available only for the ipv4

address family.

RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
vrrp 3 version 3
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

Step 6

text-authentication
Example:
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
text-authentication x30dn78k

(Optional) Configures the simple text authentication used for

Virtual Router Redundancy Protocol (VRRP) packets received
from other routers running VRRP.
When a VRRP packet arrives from another router in the
VRRP group, its authentication string is compared to the
string configured on the local system. If the strings match,
the message is accepted. If they do not match, the packet
is discarded.
All routers within the group must be configured with the
same authentication string.

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Command or Action

Purpose
To disable VRRP authentication, use the no command.
Note

Step 7

Plain text authentication is not meant to be used for

security. It simply provides a way to prevent a
misconfigured router from participating in VRRP.

Enters the IPv4 or IPv6 address family submode.

accept-mode{disable}
Example:
RP/0/RP0/CPU0:router#
(config-vrrp-virtual-router)# accept-mode disable

Step 8

priority priority

(Optional) Sets the priority of the virtual router.

Example:

Use the priority command to control which router

becomes the master router.

RP/0/RP0/CPU0:router#
(config-vrrp-virtual-router)# priority 254

The priority command is ignored while the router is the

virtual IP address owner.
To remove the priority of the virtual router, use the no
priority command.

Step 9

preempt [delay seconds] [disable]

(Optional) Sets the priority of the virtual router.

Example:

Use the preempt command to control which router

becomes the master router.

RP/0/RP0/CPU0:router#
(config-vrrp-virtual-router)# preempt delay 15

The preempt command is ignored while the router is the

virtual IP address owner.
To disable preemption, use the no preempt command.

Step 10

timer [msec] interval [force]

Example:

(Optional) Configures the interval between successive

advertisements by the master router in a Virtual Router
Redundancy Protocol (VRRP) virtual router.
To restore the default value, use the no timer command.

RP/0/RP0/CPU0:router#
(config-vrrp-virtual-router)# timer 4

Step 11

track interface type instance interface-path-id

[priority-decrement]

Note

We recommend configuring the same VRRPv3 timers

on all VRRP routers when interoperating with other
vendors.

(Optional) Configures the Virtual Router Redundancy Protocol

(VRRP) to track an interface.
Enter the no track interface type instance
interface-path-id [priority-decrement] command to
disable tracking.

Example:
RP/0/RP0/CPU0:router#
(config-vrrp-virtual-router)# track interface

Only IP interfaces are tracked.

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Enabling VRRP

Command or Action
TenGigE 0/0/CPU0/1 30

Purpose
A tracked interface is up if IP on that interface is up.
Otherwise, the tracked interface is down.
You can configure VRRP to track an interface that can
alter the priority level of a virtual router for a VRRP
virtual router. When the IP protocol state of an interface
goes down or the interface has been removed from the
router, the priority of the backup virtual router is
decremented by the value specified in the
priority-decrement argument. When the IP protocol state
on the interface returns to the up state, the priority is
restored.

Step 12

delay [minimum seconds] [ reload seconds]

Example:
RP/0/RP0/CPU0:router# (config-vrrp-virtual-router)
# delay minimum 2 reload 10

Step 13

Use the commit or end command.

(Optional) Delays the startup of the state machine when an

interface comes up, so that the network has time to settle and
there are no unnecessary state changes early after the link comes
up. The reload delay is the delay applied after the first interface
up event. The minimum delay is the delay that is applied after
any subsequent interface up event (if the interface flaps).
commitSaves the configuration changes and remains within
the configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the
configuration session.
NoExits the configuration session without committing
the configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

Enabling VRRP
Use the address command to enable VRRP on an interface, as described in the sections that follow.

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Enabling VRRP

SUMMARY STEPS
1. configure
2. router vrrp
3. interface type interface-path-id
4. address-family ipv4
5. vrrp vrid version { 2 | 3 }
6. address address
7. Use the commit or end command.

DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

router vrrp

Enables VRRP configuration mode.

Example:
RP/0/RP0/CPU0:router(config)# router vrrp

Step 3

interface type interface-path-id

Enables VRRP interface configuration mode on a specific

interface.

Example:
RP/0/RP0/CPU0:router(config-vrrp)# interface
TenGigE 0/2/0/1
RP/0/RP0/CPU0:router(config-vrrp-if)#

Step 4

Enters the IPv4 or IPv6 address family submode.

address-family ipv4
Example:
RP/0/RP0/CPU0:routerconfig-vrrp-if)#
address-family ipv4

Step 5

vrrp vrid version { 2 | 3 }

Enters the virtual router configuration submode.

Note

Example:

The version keyword is available only for the ipv4

address family.

RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
vrrp 3 version 3
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

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Verifying VRRP

Step 6

Command or Action

Purpose

address address

Enables the Virtual Router Redundancy Protocol (VRRP)

on an interface and specifies the IP address of the virtual
router.

Example:
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
address 2001:db8::/32

We recommend that you do not remove the VRRP

configuration from the IP address owner and leave the
IP address of the interface active, because duplicate IP
addresses on the LAN will result.
To disable VRRP on the interface and remove the IP
address of the virtual router, use the no address
address command.

Step 7

Use the commit or end command.

commitSaves the configuration changes and remains

within the configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the
configuration session.
NoExits the configuration session without committing
the configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

Verifying VRRP
Use the show vrrp command to display a brief or detailed status of one or all VRRP virtual routers.

SUMMARY STEPS
1. show vrrp [ ipv4 | ipv6 ] [ interface type instance interface-path-id [vrid]] [brief | detail | statistics [all]]

DETAILED STEPS

Step 1

Command or Action

Purpose

show vrrp [ ipv4 | ipv6 ] [ interface type instance

interface-path-id [vrid]] [brief | detail | statistics [all]]

Displays a brief or detailed status of one or all Virtual Router

Redundancy Protocol (VRRP) virtual routers.

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Clearing VRRP Statistics

Command or Action

Purpose
If no interface is specified, all virtual routers are
displayed.

Example:
RP/0/RP0/CPU0:router # show vrrp

Clearing VRRP Statistics

Use the clear vrrp statistics command to clear all the software counters for the specified virtual router.

SUMMARY STEPS
1. clear vrrp statistics [ ipv4 | ipv6 ] [interfacetype interface-path-id [vrid]]

DETAILED STEPS

Step 1

Command or Action

Purpose

clear vrrp statistics [ ipv4 | ipv6 ] [interfacetype

interface-path-id [vrid]]

Clears all software counters for the specified virtual router.

Example:

If no interface is specified, statistics of all virtual

routers are removed.

RP/0/RP0/CPU0:router# clear vrrp statistics

Configuration Examples for VRRP Implementation on

Cisco IOS XR Software
This section provides the following VRRP configuration examples:

Configuring accept-mode
Perform this task to disable the installation of routes for the VRRP virtual addresses.

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Configuring accept-mode

SUMMARY STEPS
1. configure
2. router vrrp
3. interface type interface-path-id
4. address-family {ipv4 | ipv6}
5. vrrp vrid version { 2 | 3 }
6. accept-mode disable
7. Use the commit or end command.

DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

router vrrp

Enables the VRRP configuration mode.

Example:
RP/0/RP0/CPU0:router(config)# router vrrp

Step 3

interface type interface-path-id

Enables the VRRP interface configuration mode on a

specific interface.

Example:
RP/0/RP0/CPU0:router(config-vrrp)# interface
TenGigE 0/2/0/1
RP/0/RP0/CPU0:router

Step 4

address-family {ipv4 | ipv6}

Enters the IPv4 or IPv6 address family submode.

Example:
RP/0/RP0/CPU0:routerconfig-vrrp-if)#
address-family ipv6
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

Step 5

vrrp vrid version { 2 | 3 }

Enters the virtual router configuration submode.

Note

Example:

The version keyword is available only for the ipv4

address family.

RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
vrrp 3 version 3

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Configuring a Global Virtual IPv6 Address

Command or Action

Purpose

RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

Step 6

Disables the installation of routes for the VRRP virtual

addresses.

accept-mode disable
Example:
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
accept-mode disable

Step 7

Use the commit or end command.

commitSaves the configuration changes and remains

within the configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the
configuration session.
NoExits the configuration session without
committing the configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

Configuring a Global Virtual IPv6 Address

Perform this task to configure the global virtual IPv6 address for a virtual router.

SUMMARY STEPS
1. configure
2. router vrrp
3. interface type interface-path-id
4. address-family ipv6
5. vrrp vrid version 3
6. address global address
7. Use the commit or end command.

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DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

router vrrp

Enables the VRRP configuration mode.

Example:
RP/0/RP0/CPU0:router(config)# router vrrp

Step 3

interface type interface-path-id

Enables the VRRP interface configuration mode on a specific

interface.

Example:
RP/0/RP0/CPU0:router(config-vrrp)# interface
TenGigE 0/2/0/1

Step 4

address-family ipv6

Enters the IPv4 or IPv6 address family submode.

Example:
RP/0/RP0/CPU0:routerconfig-vrrp-if)#
address-family ipv6

Step 5

vrrp vrid version 3

Enters the virtual router configuration submode.

Note

Example:

The version keyword is available only for the ipv4

address family.

RP/0/RP0/CPU0:router(config-vrrp-address-family)#
vrrp 3 version 3

Step 6

address global address

Configures the global virtual IPv6 address for a virtual router.

Note

Example:
RP/0/RP0/CPU0:routerconfig-vrrp-virtual-router)#
address global 2001:db8::/32

VRRP packet sizes are limited by the corresponding

interface's Maximum Transmission Unit (MTU).
This limits the maximum number of global virtual
IPv6 addresses that can be supported in a single
VRRP session. For example, the default MTU on
gigabitEthernet interfaces would allow for a
maximum of 90 VRRP global virtual IPv6 addresses
in a single session. In order to have more such
addresses, you need to increase the interface's MTU
accordingly.

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Configuring a Primary Virtual IPv4 Address

Step 7

Command or Action

Purpose

Use the commit or end command.

commitSaves the configuration changes and remains within

the configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the
configuration session.
NoExits the configuration session without committing
the configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

Configuring a Primary Virtual IPv4 Address

Perform this task to configure the primary virtual IPv4 address for a virtual router.

SUMMARY STEPS
1. configure
2. router vrrp
3. interface type interface-path-id
4. address-family ipv4
5. vrrp vrid version { 2 | 3 }
6. address address
7. Use the commit or end command.

DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

Enables the VRRP configuration mode.

router vrrp
Example:
RP/0/RP0/CPU0:router(config)# router vrrp

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Step 3

Command or Action

Purpose

interface type interface-path-id

Enables the VRRP interface configuration mode on a

specific interface.

Example:
RP/0/RP0/CPU0:router(config-vrrp)# interface
TenGigE 0/2/0/1
RP/0/RP0/CPU0:router

Step 4

address-family ipv4

Enters the IPv4 address family submode.

Example:
RP/0/RP0/CPU0:routerconfig-vrrp-if)#
address-family ipv4
RP/0/RP0/CPU0:router(config-vrrp-address-family)#

Step 5

vrrp vrid version { 2 | 3 }

Enters the virtual router configuration submode.

Note

Example:

The version keyword is available only for the

ipv4 address family.

RP/0/RP0/CPU0:router(config-vrrp-address-family)#
vrrp 3 version 2
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)

Step 6

address address

Configures the primary virtual IPv4 address for a virtual

router.

Example:
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
address 10.20.30.1

Step 7

Use the commit or end command.

commitSaves the configuration changes and remains

within the configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the
configuration session.
NoExits the configuration session without
committing the configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

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Configuring a Secondary Virtual IPv4 Address

Configuring a Secondary Virtual IPv4 Address

Perform this task to configure the secondary virtual IPv4 address for a virtual router.

SUMMARY STEPS
1. configure
2. router vrrp
3. interface type interface-path-id
4. address-family ipv4
5. vrrp vrid version { 2 | 3 }
6. address address secondary
7. Use the commit or end command.

DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

Enables the VRRP configuration mode.

router vrrp
Example:
RP/0/RP0/CPU0:router(config)# router vrrp

Step 3

interface type interface-path-id

Enables the VRRP interface configuration mode on a

specific interface.

Example:
RP/0/RP0/CPU0:router(config-vrrp)# interface
TenGigE 0/2/0/1
RP/0/RP0/CPU0:router

Step 4

Enters the IPv4 address family submode.

address-family ipv4
Example:
RP/0/RP0/CPU0:routerconfig-vrrp-if)#
address-family ipv4
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

Step 5

vrrp vrid version { 2 | 3 }

Enters the virtual router configuration submode.

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Configuring a Virtual Link-Local IPv6 Address

Command or Action

Purpose
Note

Example:

The version keyword is available only for the ipv4

address family.

RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
vrrp 3 version 3
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

Step 6

address address secondary

Configures the secondary virtual IPv4 address for a virtual

router.

Example:
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#
address 10.20.30.1 secondary

Step 7

Use the commit or end command.

commitSaves the configuration changes and remains

within the configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the
configuration session.
NoExits the configuration session without
committing the configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

Configuring a Virtual Link-Local IPv6 Address

Perform this task to either configure the virtual link-local IPv6 address for a virtual router or to specify that
the virtual link-local IPv6 address should be enabled and calculated automatically from the virtual router
virtual Media Access Control (MAC) address.
The IPv6 address space is structured differently compared to IPv4. Link-local addresses are used to identify
each interface on the local network. These addresses may either be configured or determined automatically
in a standard way using the link-layer (hardware) address of the interface (MAC address for Ethernet interfaces).
Link-local addresses have a standard format and are valid only on the local network (they cannot be routed
to, from multiple hops away).
Global unicast IPv6 addresses occupy a disjoint subset of the IPv6 address space from link-local addresses.
They can be routed to, from multiple hops away and have an associated prefix length (between 0 and 128
bits).
Each VRRP virtual router has an associated virtual link-local address. This may be configured or determined
automatically from the virtual router's virtual MAC address. The virtual MAC address must be unique on the
local network. The virtual link-local address is analogous to an IPv4 virtual router's primary virtual IPv4

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Configuring a Virtual Link-Local IPv6 Address

address, except that its virtual IP (VIP) state is always considered to be up, since duplicate address detection
is not required for addresses whose scope is local.

SUMMARY STEPS
1. configure
2. router vrrp
3. interface type interface-path-id
4. address-family ipv6
5. vrrp vrid version 3 address linklocal {address | autoconfigure}
6. Use the commit or end command.

DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

Enables the VRRP configuration mode.

router vrrp
Example:
RP/0/RP0/CPU0:router(config)# router vrrp

Step 3

interface type interface-path-id

Enables the VRRP interface configuration mode on a specific

interface.

Example:
RP/0/RP0/CPU0:router(config-vrrp)# interface
TenGigE 0/2/0/1

Step 4

Enters the IPv6 address family submode.

address-family ipv6
Example:
RP/0/RP0/CPU0:routerconfig-vrrp-if)#
address-family ipv6

Step 5

vrrp vrid version 3 address linklocal {address |

autoconfigure}

Configures the virtual link-local IPv6 address for the

virtual router.

Example:

Specifies that the virtual link-local IPv6 address should

be enabled and calculated automatically from the virtual
router virtual MAC address.

RP/0/RP0/CPU0:routerconfig-vrrp-address-family)#
vrrp 1 version 3 address linklocal
FE80::260:3EFF:FE11:6770

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Disabling State Change Logging

Command or Action

Purpose

RP/0/RP0/CPU0:router(config-vrrp-virtual-router)# Note
RP/0/RP0/CPU0:router(config-vrrp-address-family)#
vrrp 1 version 3 address linklocal autoconfigure
RP/0/RP0/CPU0:router(config-vrrp-virtual-router)#

You must disable IPv6 Duplicate Address

Detection (DAD) on an interface when the
VRRP router's virtual link-local address is the
same as the interface's link-local address. When
DAD is disabled, duplicate packets are not
flagged as duplicates.
The version keyword is available only for the
ipv4 address family.

Step 6

Use the commit or end command.

commitSaves the configuration changes and remains within

the configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the
configuration session.
NoExits the configuration session without committing
the configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

Disabling State Change Logging

Perform this task to disable the task of logging the VRRP state change events via syslog.

SUMMARY STEPS
1. configure
2. router vrrp
3. message state disable
4. Use the commit or end command.

DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

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MIB support for VRRP

Step 2

Command or Action

Purpose

router vrrp

Enables the VRRP configuration mode.

Example:
RP/0/RP0/CPU0:router(config)# router vrrp

Step 3

message state disable

Disables the task of logging the VRRP state change events via syslog.

Example:
RP/0/RP0/CPU0:router(config-vrrp)#
message state disable
RP/0/RP0/CPU0:router(config-vrrp)#

Step 4

Use the commit or end command.

commitSaves the configuration changes and remains within the

configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the configuration
session.
NoExits the configuration session without committing the
configuration changes.
CancelRemains in the configuration mode, without
committing the configuration changes.

MIB support for VRRP

VRRP enables one or more IP addresses to be assumed by a router when a failure occurs. For example, when
IP traffic from a host reaches a failed router because the failed router is the default gateway, the traffic is
transparently forwarded by the VRRP router that has assumed control. VRRP does not require configuration
of dynamic routing or router discovery protocols on every end host. The VRRP router controlling the IP
address(es) associated with a virtual router is called the master, and forwards packets sent to these IP addresses.
The election process provides dynamic fail over(standby) in the forwarding responsibility should the master
become unavailable. This allows any of the virtual router IP addresses on the LAN to be used as the default
first hop router by end-hosts.The advantage gained from using VRRP is a higher availability default path
without requiring configuration of dynamic routing or router discovery protocols on every end-host. SNMP
traps provide information of the state changes, when the virtual routers(in standby) are moved to master state
or if the standby router is made master.

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Configuring SNMP server notifications for VRRP events

Configuring SNMP server notifications for VRRP events

The snmp-server traps vrrp events command enables the Simple Network Management Protocol (SNMP)
server notifications (traps) for VRRP.

SUMMARY STEPS
1. configure
2. snmp-server traps vrrp events
3. Use the commit or end command.

DETAILED STEPS

Step 1

Command or Action

Purpose

configure

Enters global configuration mode.

Example:
RP/0/RP0/CPU0:router# configure

Step 2

snmp-server traps vrrp events

Enables the SNMP server notifications for VRRP.

Example:
RP/0/RP0/CPU0:router(config)snmp-server
traps vrrp events

Step 3

Use the commit or end command.

commitSaves the configuration changes and remains within the

configuration session.
endPrompts user to take one of these actions:
Yes Saves configuration changes and exits the configuration
session.
NoExits the configuration session without committing the
configuration changes.
CancelRemains in the configuration mode, without committing
the configuration changes.

Hot Restartability for VRRP

In the event of failure of a VRRP process in one group, forced failovers in peer VRRP master router groups
should be prevented. Hot restartability supports warm RP failover without incurring forced failovers to peer
VRRP routers.

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Configuration Examples for VRRP Implementation on Cisco IOS XR Software

Configuration Examples for VRRP Implementation on

Cisco IOS XR Software
This section provides the following VRRP configuration examples:

Configuring a VRRP Group: Example

This section provides the following configuration example of Router A and Router B, each belonging to three
VRRP groups:
Router A:
config
interface tenGigE 0/4/0/4
ipv4 address 10.1.0.1/24
exit
router vrrp
interface tenGigE 0/4/0/4
address-family ipv4
vrrp 1 version 2
priority 120
text-authentication cisco
timer 3
address 10.0.0.100
vrrp 5 version 2
timer 30
address 10.0.0.105
vrrp 5 version 2
preempt disable
address 10.0.0.200
commit

Router B:
config
interface tenGigE 0/4/0/4
ipv4 address 10.1.0.2/24
exit
router vrrp
interface tenGigE 0/4/0/4
address-family ipv4
vrrp 1 version 2
priority 100
text-authentication cisco
timer 3
address 10.0.0.100
vrrp 5 version 2
priority 200
timer 30
address 10.0.0.105
vrrp 5 version 2
preempt disable
address 10.0.0.200
commit

In the configuration example, each group has the following properties:

Virtual Router 1:

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Clearing VRRP Statistics: Example

Virtual IP address is 10. 0.0. 100.

Router A will become the master for this group with priority 120.
Advertising interval is 3 seconds.
Preemption is enabled.
Authentication is enabled.
Virtual Router 5:
Virtual IP address is 10.0.0.105.
Whichever router comes up first will become master (as preemption is disabled).
Advertising interval is 30 seconds.
Preemption is disabled.
Authentication is disabled.
Virtual Router 100:
Virtual IP address is 10.0.0.200.
Router B will become master for this group first, because it has a higher interface IP address
(10.0.0.2).
Advertising interval is the default 1 second.
Preemption is enabled.
Authentication is disabled.

Clearing VRRP Statistics: Example

The clear vrrp statistics command produces no output of its own. The command modifies the statistics given
by show vrrp statistics command so that all the statistics are reset to zero.
The following section provides examples of the output of the show vrrp statistics command followed by the
clear vrrp statistics command:

Additional References
The following sections provide references related to VRRP.
Related Documents
Related Topic

Document Title

QoS commands: complete command syntax,

Quality of Service Commands on Cisco IOS XR
command modes, command history, defaults, usage Modular Quality of Service Command Reference for
guidelines, and examples
the Cisco CRS Router

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Additional References

Related Topic

Document Title

Class-based traffic shaping, traffic policing,

low-latency queuing, and Modified Deficit Round
Robin (MDRR)

Configuring Modular Quality of Service Congestion

Management on Cisco IOS XR Modular Quality of
Service Configuration Guide for the Cisco CRS
Router

WRED, RED, and tail drop

Configuring Modular QoS Congestion Avoidance on

Cisco IOS XR Modular Quality of Service
Configuration Guide for the Cisco CRS Router

VRRP commands

VRRP Commands on Cisco IOS XR IP Addresses

and Services Command Reference for the Cisco CRS
Router

master command reference

Cisco IOS XR Commands Master List for the

Cisco CRS Router

getting started material

Cisco IOS XR Getting Started Guide for the

Cisco CRS Router

Information about user groups and task IDs

Configuring AAA Services on Cisco IOS XR System

Security Configuration Guide for the Cisco CRS
Router

Standards
Standards

Title

No new or modified standards are supported by this

feature, and support for existing standards has not
been modified by this feature.

MIBs
MIBs

MIBs Link

To locate and download MIBs, use the Cisco MIB

Locator found at the following URL and choose a
platform under the Cisco Access Products menu: http:/
/cisco.com/public/sw-center/netmgmt/cmtk/
mibs.shtml

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Additional References

RFCs
RFCs

Title

No new or modified RFCs are supported by this

feature, and support for existing RFCs has not been
modified by this feature.

Technical Assistance
Description

Link

The Cisco Technical Support website contains

http://www.cisco.com/techsupport
thousands of pages of searchable technical content,
including links to products, technologies, solutions,
technical tips, and tools. Registered Cisco.com users
can log in from this page to access even more content.

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